Oroville Dam disaster in USA – Kulekhani and Budhi-Gandaki Dams Safety

The proposed Budhi-Gandaki dam will be in one of the most seismically active areas of the world. The dam site is very close to the epicenter of very recent Gorkha earthquake measured 7.9 in Richter scale. This type of dams is highly sensitive to earthquakes. Everyone knows that the proposed Budhi-Gandaki dam is located in an area prone to big landslides, which frequently block the river resulting in impoundment of entire river flow.

By: Dr. A.B. Thapa

Implementation of big storage dam projects can provide enormously large benefits to the country.  Such    projects   apart from  generation  of  hydroelectric energy  can  provide even  greater  irrigation,  flood control  and  other benefits. Unfortunately  such  large storage  dam projects  can  equally  be  a great liability to the country  if  they are built and operated without following  strict  engineering  practices  to ensure  complete safety.

Orville Dam disaster of the USA

Very recently the news of Orville Dam disaster had been covered by media all over the world. The Oroville Dam is an earth fill embankment dam on the Feather River in the state California of the USA.  This dam is 235 meters high.  It is the tallest dam in the US.   The storage capacity of the reservoir is 4.4 cubic kilometers.  The dam serves mainly for water supply, hydroelectricity generation and flood control.  It is  interesting  to note  that  this  dam   has provided  flood  control  benefit exceeding  US $ 1.3 billion between the years  of 1987 and  1999.

 Very  recently in February  2017   the main spillway  was damaged after heavy rains and an anticipated failure of  the dam  resulted  in  mandatory  immediate  mass  evacuation of  people numbering  about 200,000  living in the river basin downstream the dam.   All those people had    to flee to safety at a very short notice leaving everything behind.  Evacuation order was partially lifted only after four days.  People  wishing  to   come  back to their    homes   were  at their  own  risk allowed  to  return back only  after  the  danger of dam failure had started to recede

It is reported in media that underestimation of the maximum flood discharge and lack     of proper repair and maintenance of the dam is the cause of the dam disaster.

Kulekhani Dam Safety

The Kulekhani high dam was in danger of being completely washed away just a few years after the completion of its construction.   We can learn from it that even minor lapses in implementation of high dam projects could have disastrous consequences for the entire country.

Government was about to take the decision to implement the Kulekhani high dam hydropower project.  It was a time when a few years earlier the world was terribly shaken by two major high dam disasters.  In December 1959 the Malpasset Dam built in France had collapsed. Similarly, in 1963 in Italy the Vaiont Dam disaster was accompanied with a 200 feet high wall of water sweeping into downstream villages, wiping out everything in its path. Both disasters were consequent upon poor geology.   I had published in our daily newspaper “The Rising Nepal” an article explaining that the geology of the Kulekhani area could be problematic.

 Storm of Criticism

Publication of my article to my great astonishment was met by a storm of widespread criticism. Even the newspaper like “Times of India” had reported that our government establishments   as well as the World Bank authorities in Washington were terribly concerned about the issue raised in my article.  Government had even published a statement to repudiate my   viewpoint on geology of Kulekhani.  Government too had good reason to be confident about the correctness of its statement because the investigation works as well as the design of that project was done by one of the world’s leading consulting firm.  It was rumored that     some critics had not hesitated even to demand punitive action against the publication.

Emergency Construction 

 All  of  a sudden our country was  shocked by the news that  the Kulekhani high dam might be on the brink of collapse  just few years  after  the completion of the  project  construction.   Canadian  Water Resources expert Dr. John Cooper had  reported after his visit to the project site that deep cracks  threatening to be extremely dangerous for the safety of the high dam have already developed over a  large  area just upstream dam around the intake structures. It was feared that a large mass of the right bank would slide and plunge into the reservoir triggering the giant waves overtopping the dam.  It became obvious that the Kulekhani dam was almost certain to collapse if prompt action is not taken to complete the necessary engineering works in time before the onset of the coming monsoon season to prevent   the dam failure.  A similar type of rock sliding into the reservoir had resulted in 1963 Vaiont Dam disaster in Italy.

Implementation of extensive civil engineering works in a very short period based on the recommendation of  a hastily  constituted   panel of top geotechnical  experts from four different countries, viz the USA, Canada, Australia and Japan helped to prevent the disaster that could  have resulted  in many thousands of deaths apart from plunging  the entire country into economic despair.  How the Kulekhani dam was on the brink of collapse must serve as a lesson to our policy makers and planners.

Any one visiting the Kulekhani dam site can even now see the extensive works carried out to prevent the dam failure.  The intake and its surroundings have been anchored by long cables to prevent them from sliding into the reservoir.  Large areas have been cleared of loose overburdens.  Special drainage tunnels have been provided to prevent the landslides.

Budhi-Gandaki High Dam Safety

Nepal is looking forward to implement in near future very ambitious 260 meters high Budhi-Gandaki double arch dam hydropower project based on design of French engineers to resolve our energy supply problem.   It appears  that  the mammoth Budhi-Gandaki High Dam Project is  proposed to be implemented turning a blind eye to irrigation and flood control benefits accruing  to  India  despite the fact that the  last BJP government of India had already constituted a  high level commission under the  Minister Suresh  Prabhu  to recommend royalty to be paid to Nepal for import  of  regulated  water.

Budhi-Gandaki dam would be higher than the Oroville dam, which is the highest dam in  the   USA.  Similarly, the volume of the Budhi-Gandaki storage reservoir would be exceeding the volume   of the Oroville dam storage reservoir.

The proposed Budhi-Gandaki dam will be in one of the most seismically active areas of the world.  The dam site is   very close to the epicenter of very recent Gorkha earthquake measured 7.9 in Richter scale. This type of dams is highly sensitive to earthquakes.  Everyone knows that the proposed Budhi-Gandaki dam is located in an area prone   to big landslides, which frequently block the river resulting in impoundment of entire river flow. Needless to say that absolute certainty of suitability of geological condition is a prerequisite for selection of the proposed double arch dam.

The type of dam proposed for the Budhi-Gandaki project must be outright rejected if there is even a slightest possibility that the geological conditions might not be satisfactory to build this type of dam.  It is obvious that due to enormity of the volume of storage reservoir the scale of the collateral damages would be too big if this dam collapsed.  Lack of through geological studies had resulted in failure of double arch dam even in France itself.  Similarly, the Vajon dam disaster in Italy reminds us that rigorous geological studies of reservoir area are equally important.

A  Panel of Experts

The Budhi-Gandaki project, which would be impounding a vast reservoir of about five cubic       kilometers, would prove to be dreadful curse to our country if the dam collapsed. Thus it is absolutely  necessary  that our government  should   constitute a panel  of internationally renowned  experts to review  rigorously  all aspects of  Budhi-Gandaki project dam  design  to ensure  that it is  safe to build the proposed dam  before taking final decision  to implement this technically ambitious high dam project.

 We should not forget the fact that even then West German Government had also constituted  a panel  of  renowned experts under a French professor,  who was chairman of the World Federation of Engineering  Geology,  to  review  the design of our Kankai high dam done under  their grant assistance by very experienced German  consulting  firm although the height of the proposed dam was only about 80 meters.

 

Source : New Spotlight